From DE 40 36 005 A1 a method of this type is known, by which the work pieces which are to be tested are rotationally symmetrical, that is, pipes and rods in particular. According to this known method oblique errors in the work piece which lie within a pregiven angular range can be specifically sensed. Each test head support has two test heads which form a pair and which are aligned toward a common test area on the surface of the workpiece. The sound beams of these two test heads are symmetrical in relation to a respective perpendicular line, which is established on the test area. One test head of the pair senses oblique errors in a positive angle range, while the other test head senses the oblique error with the same value, but in the negative angle range.
The known test head support can be rotationally adjusted, therefore oblique errors in a desired orientation can be sensed.
From EP 131 371 A1 an ultrasound test device is known, by which a test head support is rotated by means of a motor, and in which one test head is arranged at an angle to the axis of rotation.
With the known devices and methods as applied, it is not possible to check whether a workplace is free of oblique errors of any type. At the present time such tests are not prescribed by the standards and therefore are not performed, but it is becoming increasingly more important to test selective sample pieces, and possibly entire production series, in order to ascertain that no oblique errors exist at any angular position.